Python: Fix test compat for entity key validation

[moonbox3]

Motivation and Context

durabletask 1.4.0 added key validation in EntityInstanceId.__init__ that checks if "@" in key. The mock_orchestration_context fixture returned a bare Mock for new_uuid(), which became the entity key — causing TypeError: argument of type 'Mock' is not iterable.

Fix: set context.new_uuid to return a real string.

Description

A one-line fix for the test.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

Updates the DurableTask Python test suite to remain compatible with durabletask 1.4.0’s stricter EntityInstanceId key validation by ensuring the mocked orchestration context generates a real string UUID.

Changes:

• Configure mock_orchestration_context.new_uuid() to return a deterministic string value used as an entity key.

[moonbox3]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	27034	3185	88%

report-only-changed-files is enabled. No files were changed during this commit :)

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
5389	20 💤	0 ❌	0 🔥	1m 24s ⏱️